1. FIELD OF THE INVENTION
This invention relates to fabricating integrated optics, including optics in polymer films, particularly films of polystyrene doped with an azo dye.
2. THE PRIOR ART
Integrated optical circuits include optic components in a film, e.g., waveguides, optical interconnects, phase gratings and the like, which direct (or reflect) light beams in a desired direction. These components have been made in the past by a) ion exchange, a multi-step process wherein ions are exchanged in a glass substrate or b) ion milling, another multi-step process which requires a vacuum and an ion gun, both processes being relatively complex and cumbersome.
In the photobleaching prior art, U.S. Pat. No. 4,677,049 to Gritting (1987), teaches interposing a photobleachable layer between a mask and a photo-resist layer and irradiating the layers through the mask. The exposed parts of the photobleachable layer bleach to form an in-situ mask on the photo-resist layer and enhances the contrast of the mask image on such photo resist layer. Such enhanced mask images on the photo resist layer are used for photolithography in the manufacture of integrated electric circuits. Also see German Patent DE 3346716 A1 to Wegner et al. which appears to disclose the bleaching of polydiacetlylenes into photo-resist layers to make masks therein.
Also U.S. Pat. No. 4,808,285 to Chen et al. (1989) discloses the making of Y-couplers and gratings in polydiacetylene film by exposing same to a scanning electron beam or e-beam, which changes the index of refraction in such film to a certain depth. This is a cumbersome process which takes time and in which, variation in the scanning rate and/or beam intensity will vary the depth of penetration into such film. Further the scanning beam can define ragged diagonal edges in the Y-coupler 100 of FIG. 2, resulting in beam leakage thereat. Additional beam leakage can occur in the unirradiated core 310 below the Y-coupler pattern 400, as indicated in such FIG. 2.
U.S. Pat. No. 4,270,130 to Houle et al. discloses the use of dyes in a record disk that is grooved by a laser beam that forms a deformation pattern therein, such dyes being deformed by ablation during groove formation so as to render it transparent to such recording laser beam. Such beam can now be used, (even at an increased power level) for playback from such recording without destroying the recorded deformation pattern.
The prior art discloses various uses of an azo dye, e.g. methyl red, in other fields. For example, U.S. Pat. No. 4,124,390 to Kohn (1978), discloses the use of methyl red for dye toning of black and white, photographic silver images. U.S. Pat. No. 4,818,660 to Blanchet-Fincher et al (1989), discloses the use of methyl red in a photo-hardenable master, for rendering faithful proofs in the graphic arts. U.S. Pat. No. 4,360,606 to Tobias et al. (1982) discloses photo-degradeable polymer compositions based on, e.g. polystyrene, which also includes an organic photosensitizer, such as methyl red.
Accordingly, the above prior art makes no suggestion of employing an uncomplex process for forming clearly defined components for integrated optics. However, there is need and market for a process that can fabricate integrated optics including structures, circuits and components thereof, that is streamlined rather than complex and otherwise overcomes the above prior art shortcomings.
There has now been discovered a simplified (and reduced temperature) process for fabricating the above optics by locating a suitable polymer and then selectively changing the index of refraction thereof to obtain such optics.